If you're sick of seeing banner ads in your games and other smartphone apps, you can block them just by putting your phone in airplane mode.

I have no idea how I never realized this before (and I imagine this is old news to some of you), but ads need an internet connection to display on your smartphone. If you take that connection away—say, by enabling airplane mode—you won't get any more ads in your apps. I tested this on both the iPhone and my Android phone with great success: I downloaded two ad-supported apps, got bombarded by banners, and saw zero after I enabled airplane mode. It won't work for apps that need an internet connection (obviously), but it works great for games and other things like that. As always, your mileage may vary. If you have a rooted Android phone, you can just download an ad blocker, too.